Advancements in materials have led to a variety of improvements in prostheses, including the use of low weight, high strength materials and energy storage and release components. The variety of choices in prosthesis components is meant to fit with the variety of lifestyles led by lower limb amputees. For example, an elderly person that has a low activity level may not require the most advanced materials. On the other hand, a strong and physically active person may desire a prosthesis that will withstand a more rigorous lifestyle. Both high and low activity prosthesis wearers require that the prosthesis be matched with their lifestyle to ensure that the prosthesis improves their quality of life.
In order to properly assess the activity levels of lower limb amputees, the Medicare program administered by the United States Government has developed an index for assessing an amputee's functional level. The Medicare system of “K” codes provides a set of categories used to distinguish between activity levels of amputees. In the lowest level, K0, the patient does not have the ability or potential to ambulate or transfer safely with or without assistance, and a prosthesis does not enhance their quality of life or mobility. In the next lowest level, K1, the patient has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. At the next level, K2, the patient has the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces. At level K3, the patient has the ability or potential to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity beyond basic ambulation. At the highest level, K4, the patient has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels.
The clinician treating the amputee patient prescribes a prosthesis by assigning the patient to one of the K codes defining the activity level. A problem arises in that there is no objective way to measure activity level. A problem also arises because an overdesigned prosthesis may result in imbalance or instability issues for the wearer too weak to properly control the prosthesis. An underdesigned prosthesis will curtail the lifestyle of an active wearer due to having to compensate for a deficient prosthesis. Both situations usually lead to a reduction in the quality of life and rehabilitation of the patient.
Up until the present time, assessing the functionality of an amputee patient is mostly a subjective evaluation. Based on clinical experience and without any objective tool, some clinicians may decide to underprescribe a prosthesis in order to save on costs or because the clinician does not believe that the patient will be fully rehabilitated to a high functional level. On the other hand, if the clinician overprescribes a prosthesis, the prosthesis is overdesigned and underutilized, thus wasting resources that may be put to better use. In either case, overprescription or underprescription of a prosthesis may diminish the quality of life for the patient, or hamper their rehabilitation because the prosthesis is not correctly fitted.
Accordingly, a tool is necessary to properly assess the functional level of activity of a lower limb amputee.